Researchers are applying computer analysis to an expanding range of important biomechanical problems including occupational task evaluation, prosthesis design, occupant protection, and human coordination control theories. However, writing the equations of motion, constraint, and force for all but the simplest of hominoid dynamic simulations is a prodigious and tedious task. Consequently, current programs are written for specific problems and incorporate many simplifying assumptions that limit their applicability. This project's long term goal is to provide a much needed reliable, flexible analytic foundation upon which scientists in academia as well as engineers in industry can readily model hominoid, dynamic problems. In Phase I, a prototype, modeling language allowing a user to facilely describe the geometric, inertial, and surface characteristics of their particular hominoid using familiar terminology will be integrated with a similar language that can be used to describe any interacting machinery or environment. The latter language is part of a nonlinear, large displacement dynamics program which has competently demonstrated static, dynamic and modal frequency analyses. This program is produced and supported by Mechanical Dynamics, Inc. To evaluate the software design, a test problem will be chosen and solved using the prototype architecture.